Connective Tissue Flashcards
What is connective tissue (CT)?
Connective tissue is a network of fibres in a ground substance and cells; supporting tissues of the body.
What are the two main type of CT?
Specialist connective tissue (bone, cartilage etc)
‘PROPER’ connective tissue
What is Proper CT?
This is tissue developed from mesenchyme (embryological CT). It provides the mechanical support whilst also carrying blood vessels and nerves
What are the two classification of Proper CT?
Loose
Dense
Origin of ‘Proper’ CT
Mesenchyme stem cells differentiate into fibroblast cells - fibrocytes.
What is Loose CT?
Loose CT is an aggregate of loosely arranged fibres and a variety of cells.
It is the initial site of defence against bacteria, so many transient cell types migrate to loose CT from local blood vessels.
Where is Loose CT found?
It is found between different organs where it acts as both protective barrier and tissue binder.
What are the 3 types f Loose CT?
Adipose tissue: Consists mostly of fat storing cells called adipocytes. They have a rich blood supply and are twice as calorie dense as carbohydrate & protein stores. Low nuclear/cytoplasm ratio.
Found predominantly under the skin and protecting organs and neurovascular bundles.
There is very little ECM. A large number of capillaries allows the rapid storage and mobilisation of lipid molecules.
There is white and brown adipose tissue, with white being the most abundant. White contributes mostly to lipid storage and organ insulation. Brown adipose tissue is more common in infants (baby fat). It has an abundance of mitochondria in the cytoplasm which gives it a greater efficiency at metabolising stored fat/its thermogenic, releasing metabolic heat
What are the 3 types of Loose CT?
Areolar tissue: fills the spaces between muscle fibres, surrounds blood and lymph vessels, and supports organs in the abdominal cavity.
It underlies most epithelia and represents the CT component of epithelial membranes.
Contains Fibroblasts and some macrophages.
Protein Fibres are collagen and elastin.
What are the 3 types of Loose CT?
Reticular tissue: a mesh-like, supportive framework for soft organs such as the lymphatic tissue, the spleen and the liver. Reticular cells produce the reticular fibres that form the network onto which other cells attach.
What is Dense CT and what are the 2 types?
Dense CT contains more collagen fibres than Loose. As a result is displays greater resistance to stretching.
Regular
Irregular
What is dense regular CT? Name 3 examples.
Dense regular is found in tendons, ligaments, and capsules.
Tendons: parallel bundles of collagen fibres between rows of fibroblasts. The arrangement of the collagen enhances the tensile strength and resistance to stretching in the direction of the fibre orientation.
Ligaments: Similar to tendons but with less regular arrangement of collagen. Some also contain elastic fibres.
Capsules: More organised than loose CT but not truly dense regular.
What are CT composed of?
- Fibres
- Ground Substance
- Cells
The type and arrangement of fibres determines the type of CT and its function
What are the 3 types of fibres present in CT?
- Collagen
- Most abundant fibre type
- Strong, flexible with good tensile strength
- Composed of bundles of Fibrils
- Fibrils vary in diameter (15-20nm developing CT) & 200nm (dense regular CT).
- Each fibril has a distinctive banded pattern due to the arrangement of microfibrils in each fibril
- MIcrofibrils align end to end in overlapping rows with a gap between the molecules in each row
Whats the structure of Microfibrils?
They are assemblies of tropocollagen, which in turn is a spiral assembly of 3 collagen molecules arranged as a triple helix
Differences in the chains determine the type of collagen
At the end of each chain, every 3rd amino acid is a GLYCINE
GLYCINE, PROLINE & HYDROXYPROLINE are essential to for the helix
Collagen molecules are called glycoproteins
